Volute spring stabilizer

ABSTRACT

A volute spring stabilizer for controlling the trajectory of an ordnance munition such as a bomb, bomblet or canister, and consists of a flat strip of spring steel wound in a clockspring manner. The wound spring is nested in a cavity formed in the base of the munition, or may be left fully extended. Centrifugal force generated by tumbling or oscillating of the munition will cause the spring to extend to provide a stabilizing tail to enhance the stability of the munition in flight.

United States Patent 91 Hootnagle 11. 3,710,715 [4 1 Jan. 16, 1973 22Filed:

[ 54] VOILIUTE SPRING STABILIZER [75] Inventor: Wayne E. Hooinagle,Waterloo,

Iowa

[73] Assignee: The United States oi America as represented by theSecretary of the Army Nov. 24, 1970 [21] Appl. No.: 92,488

[52] US Cl. ..102/4, 102/72, 244/327 [51] Int. Cl ..F42b 25/116 [58]Field of Search .l....l02/2, 4, 7.2; 244/326, 3.27

[56] References Cited UNITED STATES PATENTS 3,494,284 2/1970 Gross..lO2/2 X 2,281,2l3 4/1942 Thaden ..lO2/2 3,282,216 11/1966 Calfee etal. ..lO2/2 FOREIGN PATENTS OR APPLICATIONS 607,239 3/1926 France"344/327 Primary Examiner-Samuel W. Engle Attorney-Edward J. Kelly,Harry M. Saragovitz, Herbert Berl and Daniel D. Sharp [57] ABSTRACT Avolute spring stabilizer for controlling the trajectory of an ordnancemunition such as a bomb, bomblet or canister, and consists of a flatstrip of spring steel wound in a clockspring manner. The wound spring isnested in a cavity formed in the base of the munition, or may be leftfully extended. Centrifugal force lgenerated by tumbling or oscillatingof the munition will cause the spring to extend to provide a stabilizingtail to enhance the stability of the munition in flight.

5 Claims, 6 Drawing Figures VOLUTE SPRING STABILIZER This inventionrelates to a volute spring stabilizer and specifically to a device forimproving the flight characteristics of a munition such as a bomb, etc.

Bombs or canister type ammunition that are fired from a mortar aresubject to tumbling and/or oscillating during flight. This impairs itstrajectory with respect to its flight path and eventual target impactsurface.

Existing stabilizers for munitions consist principally of ribbons and/orfixed tabs that are attached to the base of the munition and have notbeen too effective.

The present invention provides a greater flight orientation overexisting devices by a volute spring that is nested in compressedcondition in a recess formed in the base of the munition. The springwill normally remain in its compressed condition until tumbling oroscillation of the munition caused by centrifugal force occurs inflight, then the spring will extend outward to form an empty hollowelongated inverted frustoconical tail to overcome the aforesaid forces.Its unique configuration permits it to adjust to individual conditionsof release. Its extension will increase as release condi tions becomemore severe and will increase the restoring moment of the fallingobject. It will retract to its compressed condition in the recess as itapproaches terminal velocity and thereby produce consistent orien tationwith a short time interval. The volute spring reduces the terminalvelocity of the munition by virtue of air resistance and the throttledpassage of air between its convolutions. The device may be used witheither a projected or free falling munition.

It is therefore a principal object of this invention to provide astabilizer for controlling the flight trajectory of a munition inflight.

Another object is to provide a stabilizer for correcting the flight pathof a munition when tumbling or oscillation of the munition occurs due tocentrifugal force generated by the munition in flight.

Another object is to provide a volute spring normally confined incompressed condition within a recess formed in the base of a munitionthat will extend outward upon tumbling or oscillation of the munition toprovide a stabilizing tail.

These and other objects and advantages of the present invention will befully apparent from the following description when taken in connectionwith the annexed drawing, in which:

FIG. l is a side elevational view, partly in section of a munitionshowing the stabilizer as mounted in confined condition in a recesslocated in the base thereof;

FIG. 2 is a similar view showing the stabilizer in its extended positionat its free height;

FIG. 3 is a side elevation of a tapered blank from which the volutespring is made;

FIG. 4 is a partial view of the base ofa munition and showing thetapered spring in confined condition in a modified base;

FIG. 5 is a side elevation of a blank having equal width throughout itslength, and;

FIG. 6 is a sectional view ofa modified stabilizer and shown attacheddirectly to the flush base of a free fall type munition.

Referring to the drawing, reference character 1 designates a munition.Its rear base has an outer flange 2 and is provided with an annularrecess 3, as shown. The stabilizer of this invention is generallyindicated by 4 and in FIG. 1 it is shown as confined in the recess 3.The convolutions of the spring are indicated by 5. Spring 4 is securedat its innermost convolution (apex) to the floor of recess 3 by suitablemeans such as spot welding as at 6. For purposes of securement, the apexwill be formed of a closed coil 7 to give greater rigidity at its base.The outermost convolution of spring 4 engages flange 2 while the springis confined in recess 3.

In FIG. 3 there is illustrated a flat strip blank 8 which the volutespring is wound and is tapered along its length to a narrow outermostconvolution. The wider end of spring 8 will be at its apex. A modifiedmanner of securing the spring 8 to the floor of recess 3 is shown inFIG. 4, In this case, the floor of recess 3 is made to form a post 9 atits center to receive the wide end of spring 8.

A blank 10 is shown in FIG. 5 and consists of a flat strip having equalwidth throughout its length.

The stabilizer may be mounted in free height condition when used with afree fall type munition wherein the munition is tossed from an aircraft,etc. In this case, a volute spring 11 is attached at its apex by anysuitable means centrally to a munition having a flush base 12. When usedin conjunction with such flush base munition, the volute spring 11 mayalso have an overall diameter greater than that of the munition 12 aswhen such munition is of a very heavy weight (see FIG. 6).

It is apparent from the foregoing that a novel stabilizer has beendevised to improve the trajectory of a munition.

lWhat is claimed is:

1. In a munition having a body and a rear base, said rear base having afloor and an outer flange defining a relcess,

lthe improvement comprising, in combination l therewith, a rearstabilizer for controlling the l trajectory of said munition, said rearstabilizer comprising a volute spring, and means for attaching theinnermost convolution of said volute spring directly to the centerregion of said floor of l said recess,

lsaid spring normally being confined in compressed condition in saidrecess and having its outermost convolution in engagement with theflange of said recess, and said volute spring in the released p0sitionforming an empty hollow elongated frustoconical stabilizing surface atthe rear of said munition;

whereby when said munition is launched, said spring will extend itselfoutwardly upon centrifugal forces being generated in flight by tumblingand oscillation of said munition.

2. A stabilizer as set forth in; claim 1 wherein said volute springcomprises a flat strip of steel having equal width throughout itslength.

3. A stabilizer as set forth in claim I wherein said volute springcomprises a flat strip which is widest at the innermost convolution ofsaid spring and tapers along its length to a narrow outermostconvolution of said spring.

4. A stabilizer as claimed in claim 1 wherein the inner convolution ofsaid volute spring is spot welded to the floor of the base of saidmunition.

5. A stabilizer as set forth in claim 1 wherein said means for attachingthe innermost convolution of said spring to said floor is a postdisposed at the center region of said floor.

1. In a munition having a body and a rear base, said rear base having a floor and an outer flange defining a recess, the improvement comprising, in combination therewith, a rear stabilizer for controlling the trajectory of said munition, said rear stabilizer comprising a volute spring, and means for attaching the innermost convolution of said volute spring directly to the center region of said floor of said recess, said spring normally being confined in compressed condition in said recess and having its outermost convolution in engagement with the flange of said recess, and said volute spring in the released position forming an empty hollow elongated frustoconical stabilizing surface at the rear of said munition; whereby when said munition is launched, said spring will extend itself outwardly upon centrifugal forces being generated in flight by tumbling and oscillation of said munition.
 2. A stabilizer as set forth in claim 1 wherein said volute spring comprises a flat strip of steel having equal width throughout its length.
 3. A stabilizer as set forth in claim 1 wherein said volute spring comprises a flat strip which is widest at the innermost convolution of said spring and tapers along its length to a narrow outermost convolution of said spring.
 4. A stabilizer as claimed in claim 1 wherein the inner convolution of said volute spring is spot welded to the floor of the base of said munition.
 5. A stabilizer as set forth in claim 1 wherein said means for attaching the innermost convolution of said spring to said floor is a post disposed at the center region of said floor. 